rules_table_service.cc

/* Copyright (c) 2015, 2024, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is designed to work with certain software (including
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   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/**
  @file rules_table_service.cc
  Implementation of the service for accessing the rewrite rules table.
*/

#include <string.h>
#include <sys/types.h>

#include "my_base.h"
#include "my_bitmap.h"
#include "my_compiler.h"
#include "my_inttypes.h"
#include "mysql/service_rules_table.h"
#include "mysql/strings/m_ctype.h"
#include "sql/field.h"
#include "sql/handler.h"
#include "sql/sql_base.h"
#include "sql/table.h"
#include "sql/transaction.h"
#include "sql_string.h"
#include "thr_lock.h"

class THD;

namespace rules_table_service {

int MY_ATTRIBUTE((visibility("default")))
    dummy_function_to_ensure_we_are_linked_into_the_server() {
  return 1;
}

const char *db_name = "query_rewrite";
const char *table_name = "rewrite_rules";

int Cursor::read() {
  TABLE *table = m_table_list->table;
  // Read the next non-deleted record.
  do {
    m_last_read_status = table->file->ha_rnd_next(table->record[0]);
  } while (m_last_read_status == HA_ERR_RECORD_DELETED);
  if (m_last_read_status != 0) m_is_finished = true;
  return m_last_read_status;
}

void free_string(const char *str) { delete[] str; }

static void add_column(MY_BITMAP *map, Cursor::column_id column) {
  if (column != Cursor::ILLEGAL_COLUMN_ID) bitmap_set_bit(map, column);
}

Cursor::Cursor(THD *mysql_thd)
    : m_thd(mysql_thd),
      m_table_list(nullptr),
      m_is_finished(true),
      m_table_is_malformed(true) {
  m_table_list = new Table_ref(db_name, strlen(db_name), table_name,
                               strlen(table_name), "alias", TL_WRITE_DEFAULT);
  if (m_table_list == nullptr) return;  // Error

  m_table_list->updating = true;

  if (open_and_lock_tables(m_thd, m_table_list,
                           MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY))
    return;  // Error

  TABLE *table = m_table_list->table;
  if (table == nullptr) return;  // Error

  m_pattern_column = field_index("pattern");
  m_pattern_database_column = field_index("pattern_database");
  m_replacement_column = field_index("replacement");
  m_enabled_column = field_index("enabled");

  // The following columns are not required for the Cursor to work.
  m_message_column = field_index("message");
  m_pattern_digest_column = field_index("pattern_digest");
  m_normalized_pattern_column = field_index("normalized_pattern");

  if (m_pattern_column == ILLEGAL_COLUMN_ID ||
      m_pattern_database_column == ILLEGAL_COLUMN_ID ||
      m_replacement_column == ILLEGAL_COLUMN_ID ||
      m_enabled_column == ILLEGAL_COLUMN_ID) {
    trans_rollback_stmt(m_thd);
    close_thread_tables(m_thd);

    /*
      We are never going to use this table, we might as well get rid of the
      reference to it.
    */
    delete m_table_list;
    m_table_list = nullptr;
    m_table_is_malformed = true;
    return;  // Error
  } else
    m_table_is_malformed = false;

  add_column(table->read_set, pattern_column());
  add_column(table->read_set, pattern_database_column());
  add_column(table->read_set, replacement_column());
  add_column(table->read_set, enabled_column());
  add_column(table->read_set, message_column());

  add_column(table->write_set, enabled_column());
  add_column(table->write_set, message_column());
  add_column(table->write_set, pattern_digest_column());
  add_column(table->write_set, normalized_pattern_column());

  if (m_table_list->table->file->ha_rnd_init(true) != 0) return;  // Error

  // No error occurred, set this to false.
  m_is_finished = false;

  read();
}

const char *Cursor::fetch_string(int fieldno) {
  Field **fields = m_table_list->table->field;
  Field *field = fields[fieldno];
  if (field->is_null()) return nullptr;
  String value_buf;
  String *value = field->val_str(&value_buf);
  const size_t length = value->length();
  char *res = new char[length + 1];
  strncpy(res, value->ptr(), length);
  res[length] = '\0';
  return res;
}

int Cursor::field_index(const char *field_name) {
  TABLE *table = m_table_list->table;
  for (uint i = 0; i < table->s->fields; ++i)
    if (strcmp(table->field[i]->field_name, field_name) == 0) return i;
  return -1;
}

void Cursor::make_writeable() {
  TABLE *table = m_table_list->table;
  memcpy(table->record[1], table->record[0], table->s->rec_buff_length);
}

void Cursor::set(int colno, const char *str, size_t length) {
  TABLE *table = m_table_list->table;
  Field *field = table->field[colno];

  const CHARSET_INFO *charset = &my_charset_utf8mb3_unicode_ci;
  if (str == nullptr)
    field->set_null(0);
  else {
    field->store(str, length, charset);
    field->set_notnull(0);
  }
}

int Cursor::write() {
  TABLE *table = m_table_list->table;
  return table->file->ha_update_row(table->record[1], table->record[0]);
}

bool Cursor::had_serious_read_error() const {
  return m_last_read_status != 0 && m_last_read_status != HA_ERR_END_OF_FILE;
}

Cursor::~Cursor() {
  if (m_table_list != nullptr && m_table_list->table != nullptr)
    m_table_list->table->file->ha_rnd_end();
  delete m_table_list;
}

Cursor end() { return Cursor(); }

}  // namespace rules_table_service